Question

In an examination, one mark is awarded for every correct answer, while 1/4 mark is deducted for every wrong answer. A student answered 120 questions and got 20 marks. Which of the following pair of equations would give the result for how many questions did he answered correctly?

• A. x + y = 120; 3x + 4y = 80
• B. x + y = 120; - x + 4y = 80
• C. x + y = 60; x + 4y = 80
• D. x + y = 120; 4x + 3y = 80

Answer 1

The correct option is B

x + y = 120; - x + 4y = 80

Let No. of questions answered wrong = x
Let No. of questions answered correctly = y
Condition 1 x + y = 120 …(i)
Condition 2 x(- ¼) + y(1) = 20
⇒- x + 4y = 80 …(ii)